The present invention relates to an alarm device for protecting from overheating one or more catalytic converters mounted in series along an exhaust pipe of an internal combustion engine, for conveying the exhaust gases produced by the engine, and consequently freeing them of the noxious substances. The invention also relates to a vehicle equipped with a catalytic exhaust muffler and such an alarm device.
It is known that for ecological purposes vehicles may be equipped with one or more catalytic converters connected to the exhaust pipe of the engine of the vehicle (normally in series), through which are carried the exhaust gases from the engine, before they are discharged into the atmosphere. The known catalytic converters consist usually of exhaust mufflers (which possibly also perform the function of additional silencer), which are so-called "catalytic" mufflers, consisting of a leak-tight casing housing a support (ceramic, for example), on which is dispersed a suitable catalyst (platinum or platinum compounds, for example), capable of eliminating the noxious substances contained in the exhaust gases (essentially unburnt hydrocarbons, carbon monoxide and nitrous oxides), favouring the partial or total oxidation of the same.
Since oxidation, as is well known, is a highly exothermic chemical reaction, the temperature of the catalyst rises during the operation of the engine in proportion to the quantity of noxious substances to be oxidised and present in the exhaust gases. Therefore, if the engine produces an excess quantity of unburnt substances, there is a risk that the catalyst will be overheated to a temperature sufficient to cause the same to deteriorate. Consequently the catalytic converter may be irreparably damaged insofar as the overheating of the catalyst may lead to partial or total inactivation of the same.